<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        //console.log('a'++'b');
        console.log(NaN==NaN);
        console.log([1,2]+{a:1});
        console.log([]+{});
        console.log('a'+[]);
    </script>
</body>
</html>